The invention relates to improvements in machines for simultaneously making and trimming a plurality of streams of fibrous material, particularly for simultaneously producing at least two rod-like fillers of fibrous material of the tobacco processing industry.
It is already known to simultaneously build and process two or more streams of fibrous material, such a fragments of natural, reconstituted and/or artificial tobacco, which are formed with a surplus. The surplus must be removed prior to draping of the resulting rod-like fillers into webs of paper, imitation cork or other suitable wrapping material. As a rule, individual streams are caused to advance along closely adjacent discrete paths, and this creates problems during removal of the surplus by so-called trimming or equalizing apparatus.
U.S. Pat. No. 4,418,705 granted Dec. 6, 1983 to Seragnoli for "Method and relative manufacturing machine for simultaneously producing two continuous cigarette rods" discloses a twin rod making machine wherein the trimming apparatus comprise frustoconical surplus removing knives which operate in pairs and are disposed at opposite sides of the paths for the respective tobacco streams. The knives rotate about axes which are inclined with reference to the planes of the respective streams. The planes of the knives are inclined with reference to the planes of the tobacco streams in order to ensure that the channels wherein the streams advance cannot interfere with the surplus removing operations. A drawback of the patented machine is that the circulating cutting edges of the knives have components of movement in directions toward and away from the conveyors for the respective streams. This causes undesirable densification of the streams ahead of the surplus removing station. Such densification is unpredictable and can bring about pronounced changes in the characteristics of the streams.
A somewhat similar apparatus is disclosed in U.S. Pat. No. 4,600,020 granted July 15, 1986 to Mattei et al. for "Dual-rod cigarette manufacturing machine". The main difference is that each surplus removing apparatus comprises a frustoconical knife and a disc-shaped knife. This machine exhibits drawbacks which are similar to those of the machine disclosed by Seragnoli.